Method and apparatus for forming an electrical contact with a semiconductor substrate

ABSTRACT

The present invention is directed to a method and apparatus for plating a surface of a semiconductor workpiece (wafer, flat panel, magnetic films, etc.) using a liquid conductor that makes contact with the outer surface of the workpiece. The liquid conductor is stored in a reservoir and pump through an inlet channel to the liquid chamber. The liquid conductor is injected into a liquid chamber such that the liquid conductor makes contact with the outer surface of the workpiece. An inflatable tube is also provided to prevent the liquid conductor from reaching the back face of the workpiece. A plating solution can be applied to the front face of the workpiece where a retaining ring/seal further prevents the plating solution and the liquid conductor from making contact with each other. In an alternative embodiment, electrical contacts may be formed using an inflatable tube that has either been coated with a conductive material or contains a conductive object. The inflatable tube further provides uniform contact and pressure along the periphery of the workpiece, which may not necessarily be perfectly flat, because the tube can conform according to the shape of the periphery of the workpiece. Further, the present invention can be used to dissolve/etch a metal layer from the periphery of the workpiece.

FIELD OF THE INVENTION

[0001] The present invention relates generally to a method and apparatusfor electroplating a metal on a semiconductor substrate. Moreparticularly, the present invention is directed to a method andapparatus for forming electrical contacts on the semiconductor substrateusing a liquid conductor during the plating process. Alternatively,electrical contacts may be formed using an inflatable tube that haseither been coated with a conductive material or contains a conductiveobject. Furthermore, the present invention provides a method andapparatus for dissolving/etching a metal layer from the substrate edge.

BACKGROUND OF THE INVENTION

[0002] Plating is an important and necessary step in the highperformance chip fabrication process. When plating, it is necessary toform a good ohmic contact with a seed layer on/or near a circumferentialedge of a substrate. Different conventional techniques exist toaccomplish this task. According to one technique, for example, a greatnumber of contact fingers, upwards of 130, are used to form contactswith the seed layer on the circumferential edge of a wafer. The contactfingers, which are typically metallic, are coupled to thecircumferential edge of the wafer in accordance with any known method.

[0003]FIG. 1A illustrates a top view of a conventional configurationshowing contact fingers 12 coupled to the wafer 2 during the platingprocess. As illustrated, a large number of contact fingers 12 extendingfrom a housing 11 are evenly distributed around the circumferential edge7 of the wafer 2. The housing 11 has a ring shape corresponding to theshape of the circumferential edge 7 of the wafer 2. An electricpotential (cathode) is then applied to the wires 13 or housing 11 thatare further coupled to the contact fingers 12 within the housing 11.This, in turn, provides the electric potential to the circumferentialedge 7 of the wafer 2, thereby allowing the wafer surface to be plated.Instead of using the contact fingers 12 as described above, the electricpotential can be applied to the wafer using a ring conductor.

[0004]FIG. 1B illustrates a cross sectional view of a conventionalplating apparatus as described with reference to FIG. 1A. An entire backface 6 of the wafer 2 rests against a conventional chuck 8, and a vacuum10 is used to ensure that the wafer 2 is stationary with respect to thechuck 8 while loading and/or plating the wafer 2. Regions adjacent tothe circumferential edge 7 of the front face 4 of the wafer 2 arecoupled to the contact fingers 12 as described above. A platingsolution, typically a metal solution, is flowed in the direction ofarrow 18 to the front face 4 of the wafer 2. When an electric potentialis applied between an anode electrode 19, and the circumferential edge 7of the wafer 2, the front face 4 of the wafer can be plated with themetal species contained in the plating solution.

[0005] Contact fingers are critical components of the wafer platingprocess as they provide the necessary electrical potential to the wafer.However, conventional plating systems such as described above have manydrawbacks and disadvantages. For example, during the plating process,metal from the plating solution may be electroplated on the contactfingers, thereby generating contaminating particles. In addition, theelectroplated metal on the contact fingers increases contact resistanceresulting in a high voltage drop and failure. Moreover, over time, thecontact fingers are susceptible to corrosion and/or fatigue. Failure ofsuch contact fingers then leads to non-uniform wafer plating, which maycause irreparable damage to the semiconductor wafer, thereby resultingin lost products and revenues for the manufacturer.

[0006] Thus, there remains a need for a semiconductor substrate platingmethod and apparatus that provides plating in a dependable and reliablemanner. Accordingly, a more consistent method and apparatus forproviding an electrical contact to a semiconductor substrate duringplating is needed.

SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide a method andapparatus that provides electric potential to the wafer using a liquidconductor.

[0008] It is another object of the present invention to provide a methodand apparatus that plates the front face of the wafer while preventingthe plating solution from reaching the back face and edge of the wafer.

[0009] It is a further object of the present invention to provide amethod and apparatus that plates the front face of the wafer whilepreventing the liquid conductor from reaching the back face of thewafer.

[0010] It is yet another object of the present invention to provide amethod and apparatus that recycles the liquid conductor.

[0011] It is a further object of the present invention to provide amethod and apparatus that dissolves/etches a metal layer from theperiphery of the wafer.

[0012] It is another object of the present invention to provide a methodand apparatus that provides electric contacts to the wafer using aninflatable tube that has been coated with a conductive material.

[0013] It is a further object of the present invention to provide amethod and apparatus that plates a semiconductor workpiece such aswafers, flat panels, and magnetic films in a reliable and dependablemanner.

[0014] It is yet another object of the present invention to provide amore efficient method for establishing electrical contacts with thewafer.

[0015] These and other objects of the present invention are obtained byproviding a method and apparatus that plates a semiconductor wafer usinga liquid conductor as the electrical contacts. The present inventionincludes a liquid chamber for holding the liquid conductor during theplating process. The liquid conductor is stored in a reservoir and pumpthrough an inlet channel to the liquid chamber. A tube is inflated toseal the back face of the wafer, and the liquid conductor is injectedinto the liquid chamber such that the liquid conductor makes contactwith the circumferential edge of the wafer. An electric potential isapplied to the liquid conductor. Then, a plating solution is applied tothe front face of the wafer. After plating the wafer, the used liquidconductor is removed from the liquid chamber through an outlet channel.Subsequent wafers are processed, each time using a fresh liquidconductor.

[0016] Alternatively, the inflatable tube may be coated with aconductive material to form electric contacts with the circumferentialedge of the wafer. In this embodiment, the liquid conductor is notneeded.

[0017] A further implementation of the method and apparatus of thepresent invention is to provide an acid or etching solution to thechamber such that the metal layer on the periphery of the wafer can bedissolved/etched.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] These and other objects and advantages of the present inventionwill become apparent and more readily appreciated from the followingdetailed description of the presently preferred exemplary embodiment ofthe invention taken in conjunction with the accompanying drawings, ofwhich:

[0019]FIG. 1A illustrates a top view of a conventional configuration ofthe contact fingers coupled to a wafer during the wafer plating process;

[0020]FIG. 1B illustrates a cross sectional view of a conventionalplating apparatus;

[0021]FIG. 2 illustrates a cross sectional view of a plating apparatususing a liquid conductor in accordance with the preferred embodiment ofthe present invention;

[0022]FIG. 3 illustrates an enlarged cross sectional view of a liquidchamber in accordance with the preferred embodiment of the presentinvention;

[0023] FIGS. 4A-4B illustrate top views of a plating apparatus using theliquid conductor in accordance with the preferred embodiment of thepresent invention;

[0024]FIG. 5 illustrates a cross sectional view of a plating apparatususing a coated inflatable tube in accordance with another preferredembodiment of the present invention;

[0025] FIGS. 6A-6B illustrate top views of a plating apparatus using thecoated inflatable tube in accordance with the preferred embodiments ofthe present invention; and

[0026] FIGS. 7A-7B illustrate cross sectional views of an inflatabletube having a conductive object in accordance with the preferredembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The preferred embodiments of the present invention will now bedescribed with reference to FIGS. 2-7, wherein like components aredesignated by like reference numerals throughout the various figures. Inthe first embodiment, the present invention is directed to a method andapparatus that uses a liquid conductor as electrical contacts on thewafer during the wafer plating process. The liquid conductor ispreferably a solution containing indium, tin, gallium, mercury, acid,salt solution, or the like. Other alloys containing indium, tin,gallium, mercury, acid, salt solution, or the like may be used inaccordance with the present invention. Since the liquid conductor shouldbe in liquid phase at operating temperature and during the platingprocess, the melting point thereof will typically be in the range of 10°C. to 40° C.

[0028] In addition to the various types of solutions mentioned above,metal powders mixed with another solution may be used in accordance withthe present invention as electric contacts on the wafer during the waferplating process. For example, metal powders can be mixed with a carrierfluid, for example water, and delivered to the liquid chamber. Thus,what is important to note from this example is that metal powders mixedwith a fluid and delivered to the liquid chamber may be used in lieu ofthe various types of solutions mentioned earlier.

[0029] Furthermore, although a semiconductor wafer will be used todescribe the preferred embodiment of the present invention, othersemiconductor workpiece such as a flat panel or magnetic film may beused in accordance with the present invention.

[0030]FIG. 2 illustrates a cross sectional view of a plating apparatusin accordance with the preferred embodiment of the present invention.Similar to FIG. 1, the wafer 2 has a front face 4 and a back face 6resting against the chuck 8. A vacuum 10 is used to ensure that thewafer 2 is stationary with respect to the chuck 8 while the wafer 2 isbeing loaded and/or plated.

[0031] In the preferred embodiment of the present invention, a liquidconductor, rather than the contact fingers 12 as described withreference to FIG. 1, is used to form an ohmic contact with thecircumferential edge 7 or regions adjacent to the front face 4 of thewafer 2. The liquid conductor is stored in a reservoir 20, which may bea single reservoir or multiple reservoirs. The liquid conductor ispumped from the reservoir 20 using a conventional pump (not shown)through an inlet channel 22 and injected into a liquid chamber 24. Morethan one pump may be used to pump the liquid conductor into the liquidchamber 24 when multiple reservoirs are used.

[0032]FIG. 3 illustrates an enlarged cross sectional view of the liquidchamber 24 in accordance with the preferred embodiment of the presentinvention. To form the liquid chamber 24 and prevent the liquidconductor from flowing to the back face 6 of the wafer, a tube 26 isinflated with gas before the liquid conductor is pumped/injected intothe chamber 24. Thus, the inflated tube 26 seals the back face 6 ofwafer 2 from the liquid conductor. The tube 26 is preferably made of anelastomer or reinforced elastomer material or other material that isflexible enough to form a liquid tight seal when inflated against thewafer 2 and the retaining wall 27 of the chamber 24. The tube 26 shouldalso be strong enough to support the pressure of the injected gas.

[0033] In its deflated state, the tube 26 is attached to and rests in agroove along the retaining wall 27. When gas is injected from a gassource (not shown) through a gas line 31 that is connected to the insideof the tube 26, the tube 26 inflates until it makes a liquid tight sealagainst the edge of the wafer 2 and the retaining wall 27. At thisstage, no additional gas is injected into the tube 26. The gas may beair, nitrogen, inert gas, or any other gas that is capable of inflatingthe tube 26. A valve can be provided to adjust the pressure and the gasflow rate depending on the size of the wafer and/or size of the chamber24. Additionally, the gas line 31 can be used to remove the gas whendeflating the tube 26. The tube 26 preferably has a bicycle inner-tubeshape or bladder, corresponding to the shape of the circumferential edge7 of the wafer 2.

[0034] Referring back to FIGS. 2 and 3, a nonconductive retainerring/seal 14 is used to prevent the plating solution from reaching theback face 6 and the circumferential edge 7 of the wafer 2. The retainingring/seal 14, shaped in the ring, is positioned on the wafer 2 betweenthe liquid chamber 24 and the center of the wafer 2. The ring/seal 14 ispreferably positioned less than 10 mm from the wafer edge. The retainingring/seal 14 preferably pushes against a seed layer 5 on the front face4 of the wafer 2 holding the wafer in proper position. A liquid tightsealed is obtained with the retainer ring/seal 14 so that the liquidconductor and the plating solution are kept isolated from each other.Thus, the entire back face 6 of the wafer 2 that rests against the chuck8 and the front surface areas (typically the outer 1-10 mm surface) ofthe wafer 2, which are under the retaining ring/seal 14, are protectedfrom the plating solution.

[0035] The liquid conductor is pumped and injected into the fluidchamber 24 via the inlet channel 22. A contact ring 28 may include atunnel 30 such that the liquid conductor can be pumped/injected throughthe contact ring 28. When the liquid chamber 24 is filled, the liquidconductor 22 makes contact with the circumferential edge 7 of the wafer2. When such contact is established, an electrical potential (cathode)can be applied to the liquid conductor 22 via wire/probe 21. Thus, thecircumferential edge 7 of the wafer 2 also receives the same electricpotential. A plating solution is then flowed in the direction of arrows18 from an anode plate 19 to the front face 4 of the wafer 2. The liquidconductor 22 forms the ohmic contact with the wafer 2 such that platingis substantially uniform across the front face 4 of the wafer 2.

[0036] After plating the wafer 2, the liquid conductor in the liquidchamber 24 is removed via an outlet channel 25 to the reservoir 20 or arecycling reservoir (not shown). After removing the used liquidconductor, a fresh liquid conductor is pumped/injected into the chamber24 for processing the next wafer. The present invention contemplatesrecycling the used liquid conductor via the recycling reservoir. Usingthe recycled liquid conductor reduces the costs associated with thecurrent plating process, while providing a more efficient method ofproviding electric contacts.

[0037] FIGS. 4A-4B illustrate top views of the plating apparatus ofFIGS. 2-3 in accordance with the preferred embodiments of the presentinvention. First, from the top view, the liquid chamber 24 preferablyhas a ring shape with an inner radius 32 and an outer radius 36 from thecenter of the wafer 2. The wafer 2 has a radius 34 that is between theinner radius 32 and the outer radius 36 of the liquid chamber 24. Theliquid conductor is pumped/injected into the liquid chamber 24 throughan inlet channel 22 from the reservoir 20. Because of the ring shape,the liquid conductor in the liquid chamber 24 makes contact with theentire circumferential edge 7 of the wafer 2, which may include regionsthat are 1-10 mm from, the wafer edge. FIG. 4A also illustrates anoutlet channel 25 for removing the liquid conductor from the liquidchamber 24.

[0038] In another embodiment, multiple liquid chambers may be used inaccordance with the present invention. FIG. 4B illustrates fourcompartmentalized liquid chambers 40. The compartmentalized liquidchambers 40 have the same inner radius 32 and the same outer radius 36as in the liquid chamber 24 of FIG. 4A. The wafer radius 34 is also thesame as that illustrated in FIG. 4A. In this configuration, fourreservoirs 20 containing the liquid conductor may be used to provide theliquid conductor to each corresponding liquid chambers 40. The liquidconductor from each reservoir 20 is flowed through the correspondinginlet channels 22 into its respective liquid chambers 40. Because theliquid chambers 40 are compartmentalized, the liquid conductor containedtherein makes contact with the circumferential edge 7 of the wafer onlyat those sections. The electric potential is applied to the liquidconductors in the four liquid chambers 40, thereby resulting in theelectric potential being applied to the corresponding four sections ofthe wafer 2. Also, each liquid chamber 40 includes an outlet channel forremoving the used liquid conductor.

[0039] Although four compartmentalized liquid chambers 40 areillustrated in FIG. 4B, more or less than four chambers may be used inaccordance with the present invention.

[0040] Additionally, one skilled in the art will recognize that thepresent invention can be implemented using liquid chambers havingvarious sizes and shapes than those described in FIG. 4A and 4B.

[0041] The present invention can further be used to dissolve/etch metalfilms from the edge and regions around the edge of a semiconductorsubstrate. It is very desirable to remove spurious metal or seed layerfrom the edge or backside of the wafer, since the metal films are notaffected by chemical-mechanical process. The presence of theseundesirable metal or poorly adhering film may lead to equipmentcontamination and cross-contamination when the flakes are sheered offthe substrate. For example, the present invention may be used todissolve a Cu seed layer or spurous Cu films at the wafer edge 7 or atany portion of the wafer that is enclosed by chamber 24, or any portionof the wafer between the seal 14 and another seal (not shown) on thewafer backside 6.

[0042] After performing the metal deposition process and removing theliquid conductor from the chamber 24, a copper etching solution, such as5-20% nitric acid, or acidified 3-10% ammonium persulfate or a solutionof 5-20% sulfuric and hydrogen peroxide may be injected into the chamber24 to dissolve any undesired Cu films on the substrate. The time periodfor etching may range from 2-15 seconds, but preferably between 5-10seconds. After the edge is cleaned, the metal etchant is removed andstored in a different reservoir (not shown) than reservoir 20. The metaletchant can be flowed through inlet channel 22 and outlet channel 25to/from chamber 24. Such etching process can be performed using thechamber 24 without altering the configuration or chamber materials asdescribed earlier herein. After such etching process, the chamber 24 andthe circumferential edge 7 of the wafer 2 can be rinsed with a rinsingsolution as known in the art.

[0043]FIG. 5 illustrates a cross sectional view of a plating apparatususing a coated inflatable tube in accordance with another preferredembodiment of the present invention. FIG. 5 illustrates the wafer 2having the front face 2, the back face 6 resting against the chuck 8,and the retaining ring/seal 14 similar to those described above andillustrated in FIG. 2.

[0044] In the embodiment of FIG. 5, a tube 100 is coated with aconductive material such that when the tube 100 is inflated, the tube100 is capable of making an electric contact with the circumferentialedge 7 of the wafer 2. The tube 100 is preferably coupled to an electriccontact 102 (wire) for applying an electric potential (cathode) to thetube 100. The outer tube surface is preferably coated with a conductivematerial such as metal or polymer. The tube 100 further provides uniformcontact and pressure along the periphery of the wafer, which may notnecessarily be perfectly flat, because the tube 100 can conformaccording to the shape of the circumferential edge 7 of the wafer 2.Thus, in this embodiment, a liquid conductor is no longer needed becausethe tube 100 can be used as the cathode contact with the wafer 2.

[0045] FIGS. 6A-6B illustrate top views of a plating apparatus using thecoated inflatable tube or tubular ring in accordance with the preferredembodiments of the present invention. First, as illustrated in FIG. 6A,the tube 100 has an inner radius 104 and an outer radius 106 from thecenter of the wafer 2. The wafer 2 has a radius 108 that is between theinner radius 104 and the outer radius 106 of the tube 100. Because thetube 100 has the bicycle inner-tube shape (inflatable ring), the surfacecorresponding to the inner radius 104 of the tube 100 makes contact withthe entire circumferential edge 7 of the wafer 2. The wire 102 coupledto the tube 100 provides the necessary electric potential to the entirecircumferential edge 7 of the wafer 2 during the plating process.

[0046] In another embodiment, multiple tubes 200 may be used inaccordance with the present invention. In FIG. 6B, four tubes 200 areused, and each tube 200 has the same inner radius 104 and the same outerradius 106 as described above. The wafer radius 108 again is between theinner radius 104 and the outer radius 106. Each wire 102 is coupled toan outer surface of the corresponding tube 200. Because the tubes 200are spaced apart from each other, they form electric contacts with thecircumferential edge 7 of the wafer 2 only at four sections. An electricpotential can be applied to the four tubes 200, thereby providing thesame electric potential to the wafer 2. Additionally, more or less thanfour tubes and four wires may be used in accordance with the presentinvention.

[0047] In an alternative embodiment, instead of coating the inflatabletube with the conductive material as described above, a conductiveobject such as a plate, wire, ribbon, or the like, may be attached tothe inflatable tube. FIGS. 7A-7B illustrate enlarged cross sectionalviews of the inflatable tube 200 with the attached conductive object202. FIGS. 7A-7B illustrate the tube 200 in its deflated and inflatedstates. The conductive object 202 is attached to the tube 200 on aportion 204 such that when the tube is inflated, the conductive object202 will form a contact with the wafer 2. When the contact is madebetween the conductive object 202 and the wafer 2, a section 206 of theinflatable tube that is adjacent to the conductive object 202 forms aliquid tight seal against the wafer 2. This prevents the platingsolution from making contact with the conductive object 202. Theconductive material 202 can be attached to the inflatable tube 200 usingany conventional method such as an adhesive, or the like. Furthermore, aconductive wire or other conventional methods of applying an electricpotential to the conductive object 202 may be used in accordance withthe present invention.

[0048] The present invention enjoys general applicability in plating anyof the various metals on any type of substrate, including Cu, Cu-alloys,Au, Ni, Pt, precious metal, lead-tin solder, lead-free solder, magneticfilms such as permalloy and their respective alloys, during themanufacturing of semiconductor devices on a semiconductor substrate.Also, the embodiments of the present invention can be practiced inconventional apparatus that are adapted to employ an inflatable tube anda liquid chamber having a liquid conductor.

[0049] In the previous descriptions, numerous specific details are setforth, such as specific materials, structures, chemicals, processes,etc., to provide a thorough understanding of the present invention.However, as one having ordinary skill in the art would recognize, thepresent invention can be practiced without resorting to the detailsspecifically set forth.

[0050] Although various preferred embodiments of the present inventionhave been disclosed for illustrative purposes, those skilled in the artwill appreciate that various modifications, additions and/orsubstitutions are possible without departing from the scope and spiritof the present invention as disclosed in the claims.

I claim:
 1. A semiconductor workpiece plating apparatus for plating a front face of a semiconductor workpiece, comprising: a workpiece support; an anode; a liquid conductor adapted to make an ohmic contact with the workpiece upon application of power; and a chamber adapted to hold the liquid conductor when the liquid conductor makes the ohmic contact with the workpiece.
 2. An apparatus according to claim 1, wherein the liquid conductor comprises one of indium, tin, gallium, mercury, acidic solution, and a salt solution.
 3. An apparatus according to claim 1, wherein the liquid conductor comprises an alloy or a mixture from a group consisting of indium, tin, gallium, mercury, acidic solution, and a salt solution.
 4. An apparatus according to claim 1 further comprising a wire coupled to the liquid conductor, wherein the wire is adapted to provide an electric potential to the liquid conductor.
 5. An apparatus according to claim 1, wherein the liquid conductor is adapted to provide an electric potential to an entire circumferential edge of the workpiece.
 6. An apparatus according to claim 1, wherein the liquid conductor is adapted to provide an electric potential to predetermined areas of a circumferential edge of the workpiece.
 7. An apparatus according to claim 1 further comprising: a tube adapted to prevent the liquid conductor from reaching a back face of the workpiece; and a seal adapted to prevent the liquid conductor from reaching the front face of the workpiece.
 8. An apparatus according to claim 7, wherein the tube is inflated with a gas.
 9. An apparatus according to claim 7, wherein a section of the tube and a section of the seal form a part of the chamber.
 10. An apparatus according to claim 1 further comprising: one or more reservoirs adapted to store the liquid conductor; one or more inlet channels, wherein the one or more inlet channels are used to flow the liquid conductor from the one or more reservoirs to the chamber; and one or more outlet channels, wherein the one or more outlet channels are used to remove the liquid conductor from the chamber.
 11. An apparatus according to claim 1, wherein the liquid conductor forms the ohmic contact with the workpiece such that plating is substantially uniform across the front face of the workpiece.
 12. An apparatus according to claim 11, wherein the substantial uniformity is obtained when the liquid conductor makes ohmic contact with predetermined areas of a circumferential edge of the workpiece.
 13. An apparatus according to claim 1, wherein the liquid conductor includes a metallic powder.
 14. An apparatus according to claim 1, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 15. A semiconductor workpiece plating apparatus for plating a front face of a semiconductor workpiece, comprising: a workpiece support; an anode; and a tube adapted to make an ohmic contact with the workpiece, wherein the tube is coated with a conductive material and provides an electric potential to the workpiece upon application of power.
 16. An apparatus according to claim 15, wherein the tube is inflated with a gas.
 17. An apparatus according to claim 15, wherein the tube is formed from one of an elastomer and a reinforced elastomer.
 18. An apparatus according to claim 15, wherein the conductive material comprises one of a metal and a polymer.
 19. An apparatus according to claim 15 further comprising a wire coupled to the tube, wherein the wire is adapted to provide the electric potential to the tube.
 20. An apparatus according to claim 15, wherein the tube is adapted to provide the electric potential to an entire circumferential edge of the workpiece.
 21. An apparatus according to claim 15, wherein the tube is adapted to provide the electric potential to predetermined areas of a circumferential edge of the workpiece.
 22. An apparatus according to claim 15 further comprising a seal positioned in between the tube and the front face of the workpiece, wherein the seal is adapted to prevent a plating solution from reaching the tube.
 23. An apparatus according to claim 15, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 24. A method for plating a surface of a semiconductor workpiece, the method comprising the steps of: supporting the workpiece such that the surface of the workpiece is exposed to a plating solution, the plating solution being flowed between an anode and the workpiece; providing an electric potential to a circumferential edge of the workpiece using a liquid conductor; and plating the surface of the workpiece using the plating solution.
 25. A method according to claim 24, wherein the step of providing the electric potential to the liquid conductor comprises the step of applying the electric potential to a wire coupled to the liquid conductor.
 26. A method according to claim 24 further comprising the steps of: inflating a tube, wherein the inflated tube prevents the liquid conductor from reaching a back face of the workpiece; and injecting the liquid conductor into a chamber formed in part from the tube.
 27. A method according to claim 26 further comprising the steps of: injecting the liquid conductor into the chamber from a reservoir via an inlet channel; and removing the liquid conductor from the chamber via an outlet channel.
 28. A method according to claim 24, wherein the liquid conductor comprises one of indium, tin, gallium, mercury, acidic solution, and a salt solution.
 29. A method according to claim 24, wherein the liquid conductor comprises an alloy or a mixture from a group consisting of indium, tin, gallium, mercury, acidic solution, and a salt solution.
 30. A method according to claim 24, wherein the circumferential edge of the workpiece comprises an entire circumferential edge of the workpiece.
 31. A method according to claim 24, wherein the circumferential edge of the workpiece comprises predetermined areas of the workpiece.
 32. A method according to claim 24, wherein the liquid conductor includes a metallic powder.
 33. A method according to claim 24, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 34. A method for providing an electric potential to a surface a semiconductor workpiece, the method comprising the steps of: supporting the workpiece; injecting a liquid conductor into a chamber such that the liquid conductor makes ohmic contact with the surface of the workpiece; providing an inflated tube such that the tube seals a back face of the workpiece from the liquid conductor; and applying an electric potential to the liquid conductor in the chamber, thereby providing the electric potential to the surface of the workpiece.
 35. A method according to claim 34, wherein the step of applying the electric potential to the liquid conductor comprises the step of applying the electric potential to a wire coupled to the liquid conductor.
 36. A method according to claim 34, wherein the liquid conductor comprises one of indium, tin, gallium, mercury, acidic solution, and a salt solution.
 37. A method according to claim 34, wherein the liquid conductor comprises an alloy or a mixture from a group consisting of indium, tin, gallium, mercury, acidic solution, and a salt solution.
 38. A method according to claim 34, wherein the liquid conductor includes a metallic powder.
 39. A method according to claim 34, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 40. A method for plating a surface of a semiconductor workpiece, the method comprising the steps of: supporting the workpiece such that the surface of the workpiece is exposed to a plating solution, the plating solution being flowed between an anode and the workpiece; providing an electric potential to a circumferential edge of the workpiece using a conductive tube coated with a conductive material; and plating the surface of the workpiece using the plating solution.
 41. A method according to claim 40 further comprising the steps of: inflating the conductive tube, wherein the inflated tube makes ohmic contact with the circumferential edge of the workpiece; and providing the electric potential to the conductive tube.
 42. A method according to claim 40, wherein the inflating step comprises the step of inflating the tube with a gas.
 43. A method according to claim 40, wherein the tube is formed from one of an elastomer or a reinforced elastomer.
 44. A method according to claim 40, wherein the step of providing the electric potential to the conductive tube comprises the step of applying the electric potential to a wire coupled to the conductive tube.
 45. A method according to claim 40, wherein the conductive material comprises one of a metal and a polymer.
 46. A method according to claim 40, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 47. A method for providing an electric potential to a surface a semiconductor workpiece, the method comprising the steps of: supporting the workpiece; inflating a conductive tube coated with a conductive material such that the tube makes ohmic contact with the surface of the workpiece; and applying an electric potential to the conductive tube, thereby providing the electric potential to the surface of the workpiece.
 48. A method according to claim 47, wherein the step of applying the electric potential to the tube comprises the step of applying the electric potential to a wire coupled to the tube.
 49. A method according to claim 47, wherein the surface of the workpiece comprises an entire circumferential edge of the workpiece.
 50. A method according to claim 47, wherein the surface of the workpiece comprises predetermined areas of the workpiece.
 51. A method according to claim 47, wherein the conductive material comprises one of a metal and a polymer.
 52. A method according to claim 47, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 53. An apparatus for removing a metal layer from a circumferential edge of a semiconductor workpiece using an etching solution, comprising: a workpiece support; a chamber adapted to hold the etching solution while the etching solution removes the metal layer from the circumferential edge of the workpiece; a tube adapted to prevent the etching solution from reaching a back face of the workpiece; and a seal adapted to prevent the etching solution from reaching a front face of the workpiece.
 54. An apparatus according to claim 53, wherein the etching solution is adapted to remove the metal layer from the entire circumferential edge of the workpiece.
 55. An apparatus according to claim 53, wherein the etching solution is adapted to remove the metal layer from predetermined areas of the circumferential edge of the workpiece.
 56. An apparatus according to claim 53, wherein a section of the tube and a section of the seal form a part of the chamber.
 57. An apparatus according to claim 53, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 58. A method for removing a metal layer from a circumferential edge of a semiconductor workpiece, the method comprising the steps of: supporting the workpiece such that the circumferential edge of the workpiece is exposed an etching solution; inflating a tube, wherein the inflated tube prevents the etching solution from reaching a back face of the workpiece; and injecting the etching solution into a chamber, wherein the etching solution removes the metal layer from the circumferential edge of the workpiece.
 59. A method according to claim 58, wherein the tube is formed from one of an elastomer and a reinforced elastomer.
 60. A method according to claim 58, wherein the circumferential edge of the workpiece comprises an entire circumferential edge of the workpiece.
 61. A method according to claim 58, wherein the circumferential edge of the workpiece comprises predetermined areas of the workpiece.
 62. A method according to claim 58, wherein the workpiece comprises one of a wafer, flat panel, and a magnetic film.
 63. A semiconductor workpiece plating apparatus for plating a front face of a semiconductor workpiece, comprising: a workpiece support; an anode; an inflatable tube; and a conductive object attached to the inflatable tube, wherein the conductive object is adapted to make an ohmic contact with the workpiece and provides an electric potential to the workpiece upon application of power.
 64. An apparatus according to claim 63, wherein the conductive object comprises one of a plate, a ribbon, and a wire.
 65. A method for plating a surface of a semiconductor workpiece, the method comprising the steps of: supporting the workpiece such that the surface of the workpiece is exposed to a plating solution, the plating solution being flowed between an anode and the workpiece; providing an electric potential to a circumferential edge of the workpiece using a conductive object attached to an inflatable tube; and plating the surface of the workpiece using the plating solution.
 66. A method according to claim 65, wherein the conductive object comprises one of a plate, a ribbon, and a wire.
 67. A method for providing an electric potential to a surface a semiconductor workpiece, the method comprising the steps of: supporting the workpiece; inflating a tube having a conductive object such that the conductive object makes ohmic contact with the surface of the workpiece; and applying an electric potential to the conductive object, thereby providing the electric potential to the surface of the workpiece.
 68. A method according to claim 67, wherein the conductive object comprises one of a plate, a ribbon, and a wire. 